Manipulating the arable crop environment to enhance the activity of predatory insects.
In an attempt to diversify the agroecosystem and to improve the overwintering opportunities for natural enemies, within-field refuges were established in two winter wheat fields. These took the form of raised banks, sown with various grasses, that crossed the fields.
The new habitats provided overwintering refuge sites for many polyphagous predators, even during the first year of establishment. The effect on predation in the spring resulting from the maintenance of a predatory population within the field over the winter period, was investigated. The results of the study are discussed in the context of changes in cereal agronomy, in particular "set-aside" and "extensification" policies.